Pest threat from imported plants

The risks of importing foreign plants

Gardeners are unaware of the environmental threat posed by pests and diseases from imported plants, according to the Royal Horticultural Society(RHS).

It fears whole species of native plants might be threatened and the problem could also lead to the gradual degradation of ecosystems.

The market in imported plants has more than doubled in the last decade, from about GBP 400 million to GBP 800 million, and the gardening charity says that inevitably more exotic pests and diseases are slipping through the net. For example, it’s estimated that about 40,000 horse chestnut trees died in the UK last year due to the spread of a new disease called horse chestnut bleeding canker.

Dutch elm disease is also estimated to have led to the destruction of 30 million trees in the UK.

Risky process

At a recent conference looking into the issue, Professor Clive Brasier of the Forestry Commission said that since many of the potential threat organisms were unknown to science before they arrived, they weren’t listed as a bio-security threat in the UK.

He argued that importing plants from exotic places is a risky process, and that the current rationale governing international plant trade in plants is scientifically flawed.

The RHS is now convening a working group to develop proposals for tackling the risks of importing pests and diseases. Meanwhile, it’s urging gardeners to share their views by contributing comments to the RHS Bulletin Board , set up for this purpose.